 Dellorto DRLA Carb Question |
|
|
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
|
  |
| Ansbacher |
 Apr 25 2019, 01:10 PM
Post
#1
|
|
Senior Member  Group: Members Posts: 689 Joined: 4-July 14 From: Tampa Bay, Florida Member No.: 17,589  |
Every time I need to adjust the accelerator pumps on my Dellorto DRLA carbs, I can never remember which way to turn the nuts (clockwise or counter-clockwise) to increase the volume pumped and vice-versa. Can someone remind me? Thanks.
Ansbacher |
   |
 
|
| pilothyer |
Apr 25 2019, 04:24 PM
Post
#2
|
|
Member Group: Members Posts: 838 Joined: 21-May 08 From: N. Alabama Member No.: 9,080 Region Association: South East States |
QUOTE(Ansbacher @ Apr 25 2019, 02:10 PM)  Every time I need to adjust the accelerator pumps on my Dellorto DRLA carbs, I can never remember which way to turn the nuts (clockwise or counter-clockwise) to increase the volume pumped and vice-versa. Can someone remind me? Thanks. Ansbacher If you are referring to the pump shaft nuts, they were never meant to be used to adjust the volume of fuel pumped. You can, however adjust the volume with either a heavier accelerator pump spring (to increase the volume) or larger pump jets or possibly larger idle jets (one size up) To simply answer your question clockwise will yield a longer pump stroke and counter clockwise will yield a shorter one. |
|
|
|
| Ansbacher |
Apr 25 2019, 05:59 PM
Post
#3
|
|
Senior Member Group: Members Posts: 689 Joined: 4-July 14 From: Tampa Bay, Florida Member No.: 17,589 |
Thanks, that's what I needed to know- clockwise to lengthen the pump stroke. Not sure I know what you mean by them not being intended for accelerator pump adjustments, but in my experience they have a great effect on remedying off idle bog.
Ansbacher |
|
|
|
| porschetub |
Apr 26 2019, 02:06 PM
Post
#4
|
|
Advanced Member Group: Members Posts: 4,699 Joined: 25-July 15 From: New Zealand Member No.: 18,995 Region Association: None |
QUOTE(pilothyer @ Apr 26 2019, 10:24 AM) QUOTE(Ansbacher @ Apr 25 2019, 02:10 PM) Every time I need to adjust the accelerator pumps on my Dellorto DRLA carbs, I can never remember which way to turn the nuts (clockwise or counter-clockwise) to increase the volume pumped and vice-versa. Can someone remind me? Thanks. Ansbacher If you are referring to the pump shaft nuts, they were never meant to be used to adjust the volume of fuel pumped. You can, however adjust the volume with either a heavier accelerator pump spring (to increase the volume) or larger pump jets or possibly larger idle jets (one size up) To simply answer your question clockwise will yield a longer pump stroke and counter clockwise will yield a shorter one. (IMG:style_emoticons/default/agree.gif) excellent answer,the Dellorto handbook should have quantity per/stroke which you set to. I did my Zeniths after I rebuilt them,one was fine and the other was out a little, I found this was caused by wear on one link arm roller that runs on the throttle cam on the left carb. With this repaired I didn't have to adjust the screws as it was close enough,I did notice some wear on both throttle cams so have a new set to fit some time. Good luck. |
|
|
|
| Ansbacher |
Apr 26 2019, 03:49 PM
Post
#5
|
|
Senior Member Group: Members Posts: 689 Joined: 4-July 14 From: Tampa Bay, Florida Member No.: 17,589 |
After exhaustive reading on this subject from other sources, I am convinced that the pump jet nut controlling stroke length DOES control the VOLUME of the shot delivered, while the actual pump jet itself controls the RATE the shot is delivered.
Ansbacher |
|
|
|
| yeahmag |
Apr 26 2019, 03:52 PM
Post
#6
|
|
Advanced Member Group: Members Posts: 2,421 Joined: 18-April 05 From: Pasadena, CA Member No.: 3,946 Region Association: Southern California 
|
Exactly opposite. The stroke controls duration (which as a side effect will control volume). The jet is the main adjustment.
When and where is your bog? What is your timing at? Engine specs? What carb body, venturi, idle and main jets are in the carbs? -Aaron |
|
|
|
| rhodyguy |
Apr 27 2019, 08:52 AM
Post
#7
|
|
Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,080 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
If the nut is too tight the jets will dribble fuel. Which del book do you guys use? The CB del book is terrible.
|
|
|
|
| Ansbacher |
Apr 27 2019, 03:52 PM
Post
#8
|
|
Senior Member Group: Members Posts: 689 Joined: 4-July 14 From: Tampa Bay, Florida Member No.: 17,589 |
Thanks Rhodyguy for the heads up. I only have about 5mm of threads exposed so I think I'm OK.
I think the semantics of VOLUME and RATE got a bit unintentionally confused in this discussion. The pump jets and the stroke BOTH contribute to the overall volume of the delivered shot. Since it is not easy to change the jets themselves insitu, it only makes sense to adjust the stroke to at least govern the volume to some degree. That is why I adjust the stroke to adjust the VOLUME. Ansbacher |
|
|
|
|
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:
|
Lo-Fi Version | Time is now: 17th May 2024 - 06:14 PM |
Invision Power Board
v9.1.4 © 2024 IPS, Inc.